Re: [PATCH v7 02/10] x86/tdx: Add early_is_tdx_guest() interface

[Thomas Gleixner]

On Tue, Oct 05 2021 at 13:41, Kuppuswamy Sathyanarayanan wrote:
> +
> +#define TDX_CPUID_LEAF_ID                       0x21
> +
> +static int tdx_guest = -1;
> +
> +static inline bool early_cpuid_has_tdx_guest(void)
> +{
> +	u32 eax = TDX_CPUID_LEAF_ID, sig[3] = {0};
> +
> +	if (cpuid_eax(0) < TDX_CPUID_LEAF_ID)
> +		return false;
> +
> +	cpuid_count(TDX_CPUID_LEAF_ID, 0, &eax, &sig[0], &sig[2], &sig[1]);
> +
> +	return !memcmp("IntelTDX    ", sig, 12);
> +}
> +
> +bool early_is_tdx_guest(void)
> +{
> +	if (tdx_guest < 0)
> +		tdx_guest = early_cpuid_has_tdx_guest();
> +
> +	return !!tdx_guest;
> +}

Sigh.